Retrofit kit for integrating heat pump return lines into existing heating systems using media separation

Abstract

Summary: Standardized retrofit kit consisting of a standardized heat pump, preferably a monoblock air-to-water heat pump in outdoor installation (1), a media separator, preferably a plate heat exchanger (2), a cleaning unit, preferably a cyclone filter with magnetic separator (3), a circulation pump (4), shut-off valves with press fittings (5) and heat transfer lines (6) for quick integration into the return line of an existing central heating boiler or gas boiler in a building.

Description

[0001] The present invention relates to the realization of a hybrid heating system by retrofitting an existing building heating and hot water system with a heat pump system.

[0002] According to current technology, various types of systems are available for heating buildings. Currently, building heating systems in Germany are predominantly powered by fossil fuels. Gas accounts for 48%, heating oil for 23%, biomass for less than 10%, and electricity for less than 10%. The relatively high proportion of fossil fuels in Germany is primarily due to the large number of older buildings. Despite numerous incentives, the retrofitting or conversion of existing heating systems to heat pumps falls far short of expectations. Reasons for this include the high installation effort and costs, as well as a shortage of qualified installers. Installing a heat pump requires precise planning and sound knowledge of physics and technology, which explains the financial risks involved in such a conversion.The repeated recommendations regarding building insulation associated with the conversion further deter many property owners, as this increases the overall conversion costs. Integrating a heat pump into an existing fossil fuel-powered heating system offers a more cost-effective solution for reducing energy consumption. Domestic hot water heat pumps are commonly available for connection to the heating system's return line. These pumps draw their heat energy from the increased return temperature and then lower it further. This allows the boiler's flow temperature to be lowered while maintaining the same temperature difference for heat output. As a result, the boiler's flue gas losses and heat loss in the pipes leading to the radiators are reduced.A domestic hot water heat pump requires significantly less heat input than a central heating system, so this application can be advantageous for heating purposes. However, a disadvantage is that such a system cannot be used for space heating.

[0003] The publication DE 202015007446 describes a hybrid heating system with a coupled evaporator unit for a mini-CHP unit for partial low-temperature steam power generation. A disadvantage is the system's size, which is associated with high investment costs.

[0004] There remains a need to reduce the disadvantages of existing heating systems using fossil fuels by leveraging the advantages of a heat pump system.

[0005] The present invention is based on the objective of providing a hybrid heating system that is cost-effective and quick to implement and combines the advantages of a heat pump system with those of an existing heating system.

[0006] According to the invention, this problem is solved by a retrofit kit according to claim 1. However, from a pragmatic physical perspective, the aforementioned problems can readily be solved cost-effectively within the scope of this invention.

[0007] Due to the use of a retrofit kit as specified in claim 1, the invention, in combination with the dependent claims, offers the particularly advantageous possibility of a quick and cost-effective retrofit of the existing fossil fuel heating system, which does not need to be removed and replaced. The invention claims standardized system components for this purpose, which can be installed quickly, thus saving time. As a further advantage, the invention claims a pressureless external circuit circulation of the refrigerant due to the media separation (2) with the return line (7) of the boiler. In the described and claimed embodiment, the external circuit fittings have reduced requirements for pressure and leakage resistance. Furthermore, the claimed media separation (2) also provides inherent safety for the entire heating circuit against frost damage and leakage.Furthermore, the media separation (2) does not interfere with the demand-controlled control loop of the existing heating system. The invention claims that heat circulation to the deactivated heat pump (1) is eliminated at sub-zero temperatures during boiler operation, resulting in energy savings. In hybrid operation, the bypass valve for return temperature boosting is relieved of some of its load or becomes unnecessary. Additionally, the heating circuit (7) can be continuously cleaned by the installation of a cyclone filter () in the retrofit kit. The boiler can advantageously be used as a buffer storage tank / buffer volume when the heat pump is not operating.

[0008] In a preferred embodiment, the standardized retrofit kit according to the invention features a specific set of components that are standardized and performance-matched. This feature facilitates a quick and cost-effective retrofit of the existing heating system in a building and enables the use of a heat pump system for heating the building.

[0009] The invention comprises a standardized retrofit kit including the heat pump and all necessary components, enabling quick installation without major modifications to the existing heating system. Customer-specific planning and modifications are not required, and no special knowledge or complete replacement of the existing heating system is necessary.

[0010] All components are designed for an average single-family or two-family house and can therefore be installed within a single day. The integration method allows for various heating options: separate, i.e., boiler or heat pump (1), and hybrid, i.e., the heat pump (1) serves to raise the return temperature back to the active boiler.

[0011] The primary energy source for an air-to-water heat pump is humidity. This decreases dramatically below 0°C, while at the same time the heat losses from the building envelope increase disproportionately, resulting in a significant overall reduction in the efficiency (COP) of the heat pump.

[0012] The return temperature of the heating circuit should only be as high as necessary above the room temperature, so that a sufficient amount of heat can be emitted from the available radiating surface. The room temperature decreases when the infrared component of the radiators increases.

[0013] The COP of a heat pump depends solely on the temperature difference or temperature increase between the temperature of the outdoor medium (usually outside air) and the maximum flow temperature of the heating circuit, analogous to the Carnot efficiency. All intermediate steps are therefore irrelevant as long as sufficient heat transfer to the interior spaces is ensured via the flow of heating water.

[0014] During installation, only the return line of the shut-off heating system is disconnected, allowing the existing heating water to remain in the heating circuit. The plate heat exchanger (2) from the standardized retrofit kit is then installed in between, after which the heating system can be put back into operation even during installation.

[0015] The retrofit kit according to the invention is graduated in terms of performance, and the components are designed accordingly. The retrofit kit basically consists of the designed heat pump (primarily a monobloc air-to-water heat pump for outdoor installation) (1), a media separator (primarily a counterflow plate heat exchanger) (2), a cleaning unit (primarily a cyclone filter with magnetic separator) (3), a circulation pump (4), four shut-off valves with press fittings (5), and two heat transfer line connectors (primarily water hoses) (6) for quick integration into the return line of the existing central heating boiler or gas-fired boiler.

[0016] The advantages of media separation at the plate heat exchanger (2) far outweigh the disadvantages, such as heat transfer losses. Calculations in counterflow with a 50% glycol / water mixture on the heat pump side and water on the heating circuit side have shown that at the critical supply connections with the higher temperature, there is only a maximum temperature drop of 1.5 K across the plate walls. The greater temperature drop at the return connections is of secondary importance for the efficiency (COP) of the heat pump. The lower specific heat of the 50% glycol is compensated for by a corresponding increase in the flow rate.

[0017] The media separation completely decouples the retrofitted system from the existing heating circuit, thus largely eliminating heating circuit-related liability risks for the installer. It enables the independent operation of the respective media circuits using the additional circulation pump (4) without interfering with the existing heating control system. Furthermore, it prevents the installer from having to familiarize themselves with the control system of the existing heating system each time. The contaminated old heating water does not come into contact with the integral refrigerant heat exchanger of the heat pump, thus preventing the otherwise frequent blockages. There is no need to add or completely replace lime- and oxygen-free heating water on site. The existing heating water is also cleaned by the new cyclone magnetic separator (3), and the risk of contamination is transferred to the external plate heat exchanger (2). This can be easily and quickly replaced or, if necessary,On-site cleaning is possible. Contamination of the refrigerant heat exchanger or circulation pump within the heat pump is far more problematic. The outdoor circuit to the heat pump operates without pressure and with a frost-resistant medium. Standard flexible water pipes, hoses, and connections can be used. Problems with tightness and leakage protection are avoided. A leak does not automatically lead to the loss of valuable heating water from the entire heating circuit. Freezing of the heat pump's outdoor circuit at sub-zero outside temperatures, during shutdown, defrosting, or failure of the heat pump, its control system, or the circulation pumps is virtually impossible. If the heat pump fails, for example, due to a defect, replacement, or power outage, the heating system can continue to operate as before the conversion.

[0018] Further features and advantages of the present invention will become apparent from the exemplary embodiments described below, by means of which the invention is to be explained in more detail by way of example, without limiting the invention to these.

[0019] In an advantageous embodiment according to claim 2, it is provided that the heat output of the installed retrofit kit according to the invention can be configured in certain power levels.

[0020] The required configuration is due to the fact that various subsequent operating modes are possible or useful through the series connection of the heat pump circuit in the heating circuit.

[0021] Operating the heat pump (1) independently allows the boiler to be switched off when solar power is available and during the transitional seasons. The boiler water, which is typically between 100 and 200 liters in single-family and two-family homes, can then be used as an insulated buffer tank in addition to the heating circuit water. This allows periods of inactivity or power outages to be bridged for longer without the need for an additional buffer tank.

[0022] The hybrid operation of the heat pump serves to utilize the heat pump (1) as a return temperature booster with a high COP when solar power is unavailable and the outside temperature is above 0°C. The boiler then raises the water temperature to the required level, thus consuming less fuel. The energy-inefficient electric heating of the heat pump (1) can therefore be advantageously eliminated.

[0023] Operating the boiler alone is advantageous when there is no solar power and the outside temperature is below 0°C. For energy-efficient operation, the heat pump (1) should be switched off. Since this only occurs on a few days of the year in this country, the average annual coefficient of performance (COP) of the air-source heat pump (1) would deteriorate too much.

[0024] It is also advantageous, as claimed in claim 3, to integrate several heat pumps (1) in parallel operation into the return line (7) in order to meet a higher performance requirement.

[0025] In the further embodiment according to claim 10, an antifreeze medium, optionally containing a water additive, is proposed as the flow medium for the external circuit of the heat pump. This largely prevents icing or clogging of the refrigerant heat exchanger or the circulation pump within the heat pump (1) and the heat transfer lines (6).

[0026] The invention is described with reference to the drawing Fig. 1 is described in more detail. The schematic diagram shows the assembly of the retrofit kit within the dashed frame and its integration into the return line of an existing heating system (7). The heat pump (1) is shown as a monobloc unit installed outdoors. The other components of the retrofit kit are located indoors: the media separator (2), the cleaning unit (3), the circulation pump (4), and the shut-off valves with press fittings (5), with components (2-5) being connected to the heat pump (1) via the heat transfer lines (6) through the wall penetration. Reference sign 1 heat pump 2 media separators 3 cleaning units 4 Circulation pump 5 shut-off valve with press fitting 6 heat transfer pipes 7 Return of the heating system QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 202015007446

[0003]

Claims

[1] Standardized retrofit kit for quick integration into the return line (7) of a heating system characterized by , that it consists of a heat pump (1), a media separator (2), a circulation pump (4), the shut-off valves with screw connections (5) and heat transfer lines (6) as components which are standardized and matched in terms of performance. [2] Standardized retrofit kit according to claim 1 characterized by , that its heat output is configured in graduated power levels. [3] Standardized retrofit kit according to claims 1-2 characterized by , that a commercially available, performance-matched counterflow plate heat exchanger is integrated as a media separator (2). [4] Standardized retrofit kit according to claims 1-3 characterized by , that a flow-adapted cleaning unit (3) is integrated. [5] Standardized retrofit kit according to claims 1-4 characterized by, that the cleaning unit (3) consists of a cyclone filter with magnetic separator [6] Standardized retrofit kit according to claims 1-5 characterized by , that the heat transfer lines (6) in the outer circle consist of commercially available installation pipes or water hoses without special requirements regarding pressure resistance and leakage safety. [7] Standardized retrofit kit according to claims 1-6 characterized by that the external circuit to the heat pump consists of antifreeze and optional water additive. [8] Standardized retrofit kit according to claim 1, characterized by , that a heat pump (1) designed with sufficient power is used as an air-to-water or water-to-water heat pump. [9] Standardized retrofit kit according to claim 1 characterized by that two or more heat pumps (1) are operated in parallel to increase performance or in series to increase the flow temperature. [10] Standardized retrofit kit according to claim 1 characterized by , that instead of connecting to the return line (7) of an existing heating system, the connection is made to an existing buffer stratified storage tank, which is connected to the heating system.

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